Molded bodies of olefin-based resins are used in the fields of automobile parts such as instrument panels, packaging materials such as trays for food packaging, films for food packaging and the like, and sundries such as cases for writing materials, jackets for books, and the like from viewpoints of easiness in handling, low cost, hygiene and the like.
In recent years, copolymerization of an olefin with a monomer having a bulky substituent, which was conventionally difficult, became possible according to development of a catalyst technology. For example, the copolymerization of ethylene and vinylcyclohexane became possible by a polymerization catalyst using dimethysilyl(tetramethylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy) titanium dichloride, and studies for applying copolymers obtained by the copolymerization to various materials, have been carried out(for example, JP2000-128932 A). Further, it is important that though molecular weight of the copolymer depends on use thereof, it generally has a high molecular weight to a certain extent for providing preferable properties.